Server Set Up Guide

Security Best Practices for your Validator node

Completing this guide will provide a solid baseline to protect and secure your node.

Properly configuring and employing best practices and layered security protocols is vitally important in the context of information technology and networks, including blockchain networks. Here are some reasons that highlight its importance:

  1. Protection of sensitive data: Best practices and security protocols help protect sensitive data from attacks and unauthorized access. This includes personal, financial, medical or other sensitive data that may be at risk if adequate security measures are not implemented.
  2. Prevention of breaches and cyberattacks: Proper configuration and use of security layers help prevent security breaches and cyberattacks. These measures include firewalls, intrusion detection systems, data encryption, user authentication, and other techniques to detect and prevent malicious activity.
  3. Maintenance of the integrity of the systems: The adequate configuration of security layers helps to maintain the integrity of the systems and the information. This ensures that data is not altered or modified without authorization, and that systems function reliably and consistently.
  4. Compliance with regulations and regulations: Security best practices and proper protocols are essential to comply with regulations and regulations related to privacy and data security. Failure to comply with these regulations can result in legal penalties, fines, and damage to an organization’s reputation.
  5. Protection of the organization’s reputation: A security breach or a successful attack can have a significant impact on the reputation of an organization. Properly configuring security layers and following best practices helps protect an organization’s image and trust with its customers, business partners, and the general public.
  6. Resilience against new threats: Cyber threats are constantly evolving, so it is crucial to stay current with security best practices and protocols. By correctly configuring security layers and following best practices, you can improve the resilience of systems against new threats and emerging attacks.

In summary, configuring correctly and employing best practices and layered security protocols is essential to protect data, prevent security breaches, comply with regulations, maintain system integrity, and protect the organization’s reputation. Additionally, it helps ensure resilience against ongoing cyber threats. In addition, if you want to apply to be a validator within the KalyChain network, you will have to demonstrate that you are capable of managing and administering our security standards.


Operating System: Ubuntu 20.04 LTS 64 bits


Hardware minimum desired
CPU’s: 2 4
Memory: 4 Gb 8 Gb
Hard Disk: 100 Gb 1000 Gb
  • a SSH client or terminal window access on a local computer.

In case you need a SSH client for your operating system, refer to:

:man_mage: Mandatory: Create a non-root user with sudo privileges

Begin by connecting to your Ubuntu Server with your SSH client.

ssh [email protected]

Create a new user called kaly

sudo useradd -m -s /bin/bash kaly

{% hint style=”info” %} the user name¬†kaly¬†is only an example you can make any user name you wish {% endhint %}

Set the password for kaly user

sudo passwd kaly

Add kaly to the sudo group

sudo usermod -aG sudo kaly

ūüĒź¬†Mandatory:¬†Disable SSH password Authentication and Use SSH Keys only

{% hint style=”info” %} The basic rules of hardening SSH are:

  • No password for SSH access (use private key)
  • Don’t allow root to SSH (the appropriate users should SSH in, then¬†su¬†or¬†sudo)
  • Use¬†sudo¬†for users so commands are logged
  • Log unauthorized login attempts (and consider software to block/ban users who try to access your server too many times, like fail2ban)
  • Lock down SSH to only the ip range your require (if you feel like it) {% endhint %}

Create a new SSH key pair on your local machine. Run this on your local machine. You will be asked to type a file name in which to save the key. This will be your keyname.

ssh-keygen -t ed25519

Your SSH key pair is stored in your home directory. For example, if your keyname was mySSHkey, then your private SSH key is mySSHkey and your public SSH key is

IMPORTANT: Make multiple backup copies of your private SSH key file to external storage, such as a USB backup key, for recovery purposes.

Verify the contents of your private SSH key file before moving on.

cat <keyname>

It should look similar to this example.



Transfer the public key to your remote node. Replace <> appropriately.

ssh-copy-id -i $HOME/<> [email protected]

Login with your new kaly user

ssh [email protected]

Disable root login and password based login. Edit the /etc/ssh/sshd_config file

sudo nano /etc/ssh/sshd_config

Locate PubkeyAuthentication and update to yes. Delete the #, if needed.

PubkeyAuthentication yes

Locate PasswordAuthentication and update to no

PasswordAuthentication no

Locate PermitRootLogin and update to prohibit-password

PermitRootLogin prohibit-password

Locate PermitEmptyPasswords and update to no

PermitEmptyPasswords no

Optional: Locate Port and customize it your random port.

Port <your random port number>

A valid random port # ranges from 1024 thru 49141.

Check that the port is not already used by other services. Replace <port> with your random port #.

sudo ss -ntlp | grep :<port>

Empty response means the port is good.

A response with red numbers means the port is already used. Choose another port.

Validate the syntax of your new SSH configuration.

sudo sshd -t

If no errors with the syntax validation, restart the SSH process

sudo systemctl restart sshd

Verify the login still works

Standard SSH Port 22

ssh [email protected]


Custom SSH Port

ssh [email protected] -p <custom random port number>


Optional: Make logging in easier by updating your local ssh config.

To simplify the ssh command needed to log in to your server, consider updating your local $HOME/.ssh/config file:

Host kaly-node
  User kaly
  HostName <node.ip.address>
  Port <custom random port number>

This will allow you to log in with ssh kaly-node rather than needing to pass through all ssh parameters explicitly.

ūü§Ė¬†Mandatory:¬†Update your system

It’s critically important to keep your system up-to-date with the latest patches to prevent intruders from accessing your system.

sudo apt-get update -y && sudo apt dist-upgrade -y
sudo apt-get autoremove
sudo apt-get autoclean

Enable automatic updates so you don’t have to manually install them.

sudo apt-get install unattended-upgrades
sudo dpkg-reconfigure -plow unattended-upgrades

Reboot your system to enable the upgrades.

sudo reboot

ūüßĪ¬†Mandatory:¬†Configure your Firewall

The standard UFW firewall can be used to control network access to your node.

With any new installation, ufw is disabled by default. Enable it with the following settings.

  • If you used a custom random SSH port, replace “22” with your actual port #.
# By default, deny all incoming and outgoing traffic
sudo ufw default deny incoming
sudo ufw default allow outgoing
# Allow ssh access
sudo ufw allow 22/tcp
# Allow execution client port
sudo ufw allow 30303
# Allow rpc port
sudo ufw allow 8545
# Allow ws port
sudo ufw allow 8546
# Enable firewall
sudo ufw enable

If you dont want to make RPC or WS calls to your node remotely Omit allowing ports 8545 and 8546.

Confirm the settings are in effect.

sudo ufw status numbered

Example of properly configured ufw status for Lighthouse.

     To                         Action      From
     --                         ------      ----
[ 1] 22/tcp                     ALLOW IN    Anywhere
[ 2] 30303                      ALLOW IN    Anywhere
[ 3] 8545                       ALLOW IN    Anywhere
[ 4] 8546                       ALLOW IN    Anywhere
[ 5] 22/tcp (v6)                ALLOW IN    Anywhere (v6)
[ 6] 30303 (v6)                 ALLOW IN    Anywhere (v6)
[ 7] 8545 (v6)                  ALLOW IN    Anywhere (v6)
[ 7] 8546 (v6)                  ALLOW IN    Anywhere (v6)

Note for Grafana Users: Do not expose Grafana (port 3000) to the public internet as this invites a new attack surface! A secure solution would be to access Grafana through a ssh tunnel.

Example of how to create a ssh tunnel:

ssh -N -v [email protected] -L 3000:localhost:3000


[ Optional ] Whitelisting, which means permitting connections from a specific IP, can be setup via the following command.

sudo ufw allow from <your local daily laptop/pc>
# Example
# sudo ufw allow from

‚õďÔłŹ¬†Mandatory:¬†Install Fail2ban

Fail2ban is an intrusion-prevention system that monitors log files and searches for particular patterns that correspond to a failed login attempt. If a certain number of failed logins are detected from a specific IP address (within a specified amount of time), fail2ban blocks access from that IP address. {% endhint %}

sudo apt-get install fail2ban -y

Edit a config file that monitors SSH logins.

sudo nano /etc/fail2ban/jail.local

Add the following lines to the bottom of the file.

ūüĒ•¬†Whitelisting IP address tip: The¬†ignoreip¬†parameter accepts IP addresses, IP ranges or DNS hosts that you can specify to be allowed to connect. This is where you want to specify your local machine, local IP range or local domain, separated by spaces.

# Example
ignoreip =


enabled = true
port = <22 or your random port number>
filter = sshd
logpath = /var/log/auth.log
maxretry = 3
# whitelisted IP addresses
ignoreip = <list of whitelisted IP address, your local daily laptop/pc>

Save/close file.

Restart fail2ban for settings to take effect.

sudo systemctl restart fail2ban

ūüźĽ¬†Optional: Disable root account

System admins should not frequently log in as root in order to maintain server security. Instead, you can use sudo execute that require low-level privileges.

# To disable the root account, simply use the -l option.
sudo passwd -l root
# If for some valid reason you need to re-enable the account, simply use the -u option.
sudo passwd -u root

:tools: Optional: Setup Two Factor Authentication for SSH

{% hint style=”info” %} SSH, the secure shell, is often used to access remote Linux systems. Because we often use it to connect with computers containing important data, it‚Äôs recommended to add another security layer. Here comes the two factor authentication (2FA). {% endhint %}

sudo apt install libpam-google-authenticator -y

To make SSH use the Google Authenticator PAM module, edit the /etc/pam.d/sshd file:

sudo nano /etc/pam.d/sshd

Add the following line:

auth required

Now you need to restart the sshd daemon using:

sudo systemctl restart sshd.service

Modify /etc/ssh/sshd_config

sudo nano /etc/ssh/sshd_config

Locate ChallengeResponseAuthentication and update to yes

ChallengeResponseAuthentication yes

Locate UsePAM and update to yes

UsePAM yes

Save the file and exit.

Run the google-authenticator command.


It will ask you a series of questions, here is a recommended configuration:

  • Make tokens ‚Äútime-base‚ÄĚ”: yes
  • Update the¬†.google_authenticator¬†file: yes
  • Disallow multiple uses: yes
  • Increase the original generation time limit: no
  • Enable rate-limiting: yes

You may have noticed the giant QR code that appeared during the process, underneath are your emergency scratch codes to be used if you don’t have access to your phone: write them down on paper and keep them in a safe place.

Now, open Google Authenticator on your phone and add your secret key to make two factor authentication work.

Note: If you are enabling 2FA on a remote machine that you access over SSH you need to follow steps 2 and 3 of this tutorial to make 2FA work.

ūüß©¬†Optional: Secure Shared Memory

One of the first things you should do is secure the shared memory¬†used on the system. If you’re unaware, shared memory can be used in an attack against a running service. Because of this, secure that portion of system memory.

To learn more about secure shared memory, read this article.